Rotary machines, such as steam and gas turbines used for power generation and mechanical drive applications, are generally large machines comprising rotating and stationary components. In operation, such rotary machines depend on the controlled flow of air between these components. In turbines, for example, high pressure air flowing through various turbine stages can pass through a series of stationary and rotating components. When passing through certain stationary and rotating components, air leakage, such as from an area of higher pressure to an area of lower pressure, is generally undesirable. Partially for this reason, seals between the stationary and rotating components can be used. In addition to controlling air leakage, seals can be used to direct air flow away from some components, such as bearing housings and rotor components, and towards other components, such as to purge cavities. The efficiency of rotary machines can depend on the ability of such seals to prevent air leakage and to direct the flow of air among rotating and stationary components.
A number of different seal designs have been used in rotary machines. These seals can include: “pumpkin teeth” seals; labyrinth seals; honeycomb seals; and brush seals. These designs are intended to minimize air leakage across components and to direct air flow between components. Because these seals can be positioned between rotating and stationary components, such seals can be in physical contact with these components. When the machine is in operation, friction between the rotating and stationary component can cause the seal to deteriorate. As the seal wears away, the machine's efficiency can suffer and the probability of failure can increase.
Thus, there is a need for an improved seal for reducing air leakage and controlling air flow in a rotary machine. More specifically, there is a need for systems, methods, and an apparatus for providing a magnetic seal.